Sinking a Lemon

Here's another cool density experiment to try with your kids.  We actually tried this with an orange a year or so ago, but my daughters wanted to try this with a lemon.  The idea is to take a lemon and determine whether it sinks or floats in water.  I started out by asking my daughters what they thought would happen and why and then we tested it.

The lemon is less dense than water and floats in the water.  We next peeled off the rind.  I asked my daughters if they thought the rind would float.  Then we tested it and sure enough, the rind floats.  The next question is whether the meat of the lemon floats.  If the lemon itself floated and the rind floats, the expectation is that the meat will sink, given it is more dense than water.  We showed this to be true with an orange.  However, when we dropped in the lemon meat, it still floated!

This was NOT expected.  So what's going on here?  This is where science is amazing.  Because this experiment didn't turn out as expected, it led us to ask other questions and do other tests on the lemon.  We then tore the lemon into individual wedges and tested the wedges.  Some of the wedges floated, while others, such as the one below, sank.  

Turns out, this was an old lemon, having been in our fridge for close to two months.  In that time, it appears that some wedges were filled with more air and less juice, resulting in a lower density than water.  Although some wedges sank, overall, the lemon was less dense than water (even without the rind) and floated.  Very cool!  Sometimes the best science occurs when things don't work out as expected!